The present invention relates to a muffler for a two-stroke internal combustion engine, especially for a portable working tool such as a motor chain saw, a cut-off saw, hedge trimmer, cutter etc., wherein the muffler comprises a housing having an exhaust gas inlet and an exhaust gas outlet and a flow channel formed by shaped sheet metal members inserted into the housing, whereby the flow channel extends at least over a portion of its length along the plane of the sheet metal members.
From European patent application 0 664 380 a muffler is known which is comprised of an inner shell of two sheet metal members resting on one another and a housing shell comprised of two outer sheet metal members resting on one another. The inner shell has a circumferential edge which is secured between clamping depressions of the housing shell in a spring-elastic manner. An exhaust gas inlet and an exhaust gas outlet are positioned at opposed sides of the housing in the area of the connecting surfaces of the two outer sheet metal members and between the exhaust gas inlet and the exhaust gas outlet the flow channel extends that is formed by a respective shaping of the inner sheet metal members or by inserted tube members. The extension of the flow channel between the exhaust gas inlet and exhaust gas outlet is meanderlike.
In German Patent 42 06 839 a muffler for an internal combustion engine is disclosed whereby in the muffler a catalyst is arranged. The muffler comprises a two-part housing, i.e., a muffler body and a muffler cover which are detachably connected to one another. In the housing a thermal and acoustic insulation is provided which rests at the inner upper surface of the muffler cover. At the inner upper surface of the thermal and acoustical insulation layer a catalyst layer comprised of a catalyst fabric is positioned. A porous securing device is provided in the muffler cover which forces the thermal and acoustic insulation layer as well as the catalyst layer against the muffler cover whereby the porous securing device has an inner surface along which the exhaust gas will flow.
It is an object of the present invention to provide a muffler of the aforementioned kind that is of a simple design but, despite a small constructive size, provides minimal noise emission.